Thanks, but i still donot know

what is real difference between I485 pending and I485 pending plus using EAD or AP. A lawer told me there are no differences. It seems to make no sense that: if EAD is used, one can not return to previous visa status, but if EAD is not used while I485 pending,one is still able to return to previous status if I485 is denied. I would be very apprecaited if you could provide further information.